Hello there. I went and asked about these from Masahiro Ito on his BBS board. Here's what I posted and his reply. I think we got this clear now:

Me: "There has been alot of talk about the mouth and ear image's resemblance in Silent Hill 3, and nobody seems to fully understand them. Could you explain even a little what does the smiling mouth and bleeding ear photos mean? And the nurses red mouths?

Thank you for such awesome and inspiring work!"

Ito: "Hi Hasuak.

"Mouth" means Alessa's shrieking insanity from the bottom of her heart.SH3's "Another world" where Heather enters is reflected in the Alessa's conscious.Alessa was bullied at school and suffered from her mother's cruelty.(Incidentally, mouth in SH2 means Mary's shrieking insanity.)

Bleeding ear's case,I wanted to express Another world's personality like human.(That ear is Alessa's.)But I didn't wanna use the "eye", because I didn't use it in Silent hill series creature's design.Bleeding means Alessa's conscious is mad.